Improved resolution of cave weta diversity (Orthoptera: Rhaphidophoridae): ecological implications for Te Paki, Far North, New Zealand

Abstract

The New Zealand cave weta fauna is large and diverse but poorly described. This study aimed to improve the strategies for cave weta identification and, in doing so, build an understanding of population dynamics and distribution of the taxon across three habitat types in the Te Paki Ecological District. Species identification used morphological traits and metric analysis of specimens in pitfall traps. Although nearly half the individuals were juveniles (< 10 mm long) that could not readily be distinguished from one another, four species were identified from the larger specimens. Capture rates of cave weta varied by species, habitat, month and the interactions of these variables. Nearly half of all identified cave weta individuals in our sample were Neonetus variegatus, which was abundant across all three habitats (pine forest, native forest and shrubland) throughout the year, but were caught in pitfall traps in the greatest numbers in some pine forest sites. A species of Pachyrhamma was also abundant and showed seasonal variation in capture rate, but no adults were captured by pitfall traps. Talitropsis sp. and Pallidoplectron sp. were least frequent in our sample. Taxonomic resolution improves ecological inference, but, as with other invertebrates, trapping method and design influence sampling outcome among species.